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I was having Ubuntu 10.04 Server running over a software raid 0. Yesterday, I left it running continuously for 10 hours, when I came back, the computer became weird. I cannot shut it down. It was saying "Bus error" or something similar to that. So I force a shutdown by holding power button for 4 seconds. Then I turn it on back. And here come disaster: The raid was broken. System kept dumping out "Failed command: READ DMA EXT". I tried to run fsck.ext4 /dev/md0 from the Alternate CD rescue mode, but fsck.ext4 then said: "Attempt to read block from filesystem resulted in short read". So I use a Hiren CD and run the hard drive scanner and find 12 bad sectors on second hard drive (and at the very end of the drive: more than 80% from the beginning I recall) The told the software to fix the 12 bad sectors but I doubt if Ubuntu understand the fix.

I again ran the Alternate CD rescue mode again, and did e2fsck /dev/sda but it was saying device or resource is busy.

God and geeks, how come that 12 bad sectors mess up my whole RAID. What should I do to have my RAID and Ubuntu work again?

P/S: Once I get stuff work back, I'll switch to RAID 5. I swear.

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software raid often means trouble – Pitto Mar 27 '11 at 11:20
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I'm really sorry but the recovery process for an error on a RAID 0 volume is "restore from backup, which hopefully is up to date". That's why very few people will recommend you use it for anything. – DJ Pon3 Mar 27 '11 at 12:05
First you ran fsck.ext4 /dev/md0, but after the Hiren CD manipulation you ran e2fsck /dev/sda. Why different devices? Shouldn't it be the same device, assuming your sectors are repaired? – grs Mar 27 '11 at 16:25
If you are running RAID0 and you then went and manipulated one of the disks manually (as gstoynev mentions), you're totally stuffed. End of story. – Mark Henderson♦ Mar 27 '11 at 23:42
@Pitto people with BS in mind are the real trouble, actually. My LinuxSoftRAIDs work for years w/o any reason to blame it. – poige Mar 28 '11 at 2:03
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3 Answers

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RAID 0 has no redundancy so errors will break the entire array. Are you confusing it with RAID 1 (mirrored)?

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Can you tell us how your RAID 0 array was set up? I had the impression that it consists of 2 physical drives: /dev/sda + /dev/sdb and the resulting device is /dev/md0. Now you are talking about /dev/md1. Does /dev/md0 = /dev/sda1 + /dev/sdb1 and /dev/md1 = /dev/sda2 + /dev/sdb2? And if so - how you expect to repair the md0 filesystem (which is spread across 2 devices/partitions) when you run it only on one of these devices? This is RAID 0, not 1.

The funny thing is none of /dev/sda1, /dev/sda2, /dev/sdb1, /dev/sdb2 is fsck-able without error.

-> is it the same "Superblock invalid" error?

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Yes, it is the same "Superblock invalid" error – Phuong Nguyen Apr 3 '11 at 2:34
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up vote -1 down vote

device or resource is busy

This error message is because your RAID daemon is on. In case of RHEL/CentOS you can stop RAID service/daemon by the command: 

mdadm --stop

After stopping RAID, check the file system using fsck -fyC /dev/sda

f - stands for force
y - stands for yes to all
C - stands for progress bar
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No - the problem is (as JamesRyan says) the filesystem is goosed because RAID 0 offers no redundancy. – DaveG Mar 27 '11 at 15:59
Okay, so I stopped /dev/md0 & /dev/md1 => /dev/sda & /dev/sdb can be checked now. When I run fsck /dev/sda & fsck/dev/sdb I received "Superblock invalid" error. I guess because /dev/sad is the whole device and not a valid ext{2,3,4}. The funny thing is none of /dev/sda1, /dev/sda2, /dev/sdb1, /dev/sdb2 is fsck-able without error. I guess I should throw them all and try a scratch raid 5. – Phuong Nguyen Mar 27 '11 at 16:44
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